/* 
  返回顶部样式
  <div class="top top_fixed">
    <a id="tops" href="#">回顶部</a>
  </div>
*/
.top_fixed {
  position: fixed;
  right: 4%;
  bottom: 4rem;
  z-index: 999;
}

.top {
  width: 3rem;
  height: 3rem;
  border: 1px solid #818181;
  border-radius: 50%;
  background-color: rgba(0, 0, 0, 0.7);
  display: none;
}

.top a {
  display: -webkit-flex;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
  font-size: 0.7rem;
  color: #fff;
}